BUGS:
Doesn't report SHA1/SHA2 digest changes or directory file changes for link targets.

FEATURES TO ADD:

Add ability to auto-generate a configuration via interactive questions
about directories off the root directory (descending the tree on
demand).

Add ability to send notifications, with email addresses definable
per-set and per-tree.

Add ability to initialize new trees added to the conf file without
initializing anything else or having to put those trees into a special
set.  Perhaps create an implicit set called "new" or "uncreated" that
includes all and only trees without specifications.

Per-user sigtree conf files (~/.sigtree.conf ?), when run as non-root.
Allow setting root dir, spec dir in ~/.sigtree.conf; perhaps also
via environmental variables.

Add keyword(s) for cyclog/multilog dirs, so that it won't keep
commenting on every new addition to/deletion from the log directory
unless it somehow violates the format of a cyclog/multilog dir.
The reason this can't currently be done with exceptions is that
there is no flag to ignore file adds/deletions.  (With regexps,
you could get close, by having it ignore files in the directory
that are of the appropriate format.)

Allow the ability to use reg exps (or limited regexps) in exception:
fields.  (Will require changing the subroutines underlying the
determination of primary set...)  Useful for, e.g., measuring
different things based on file suffixes.

Add functionality to facilitate remote execution (i.e., keep 
specifications on a secure bastion host, scp them (and the code)
out to each remote host, run the check, and summarize changes
for all hosts; run updates on all hosts and scp the specifications
back to the bastion host).  Use a client/server architecture.
GUI?  Showing hosts, files changed/added/deleted?

Or: add ability to detect changes in real-time and report back
to a central server.

Add the ability to attempt to correlate file changes with entries in
logs (in particular, in the sudo log --/var/log/security, where we can
come up with a username, and perhaps also with /var/log/messages).

Add support for Windows and MacOS.  (Will need to use File::Basename
in a lot of places.)  (Actually, this should already work on Mac OS X
now--or Cygwin.)

Add the ability to generate an mtree file from a spec. (low priority)
(And vice versa?)
